3.4- DNA Replication

Question 1

What does it mean when DNA Replication is semi-conservative

Answer 1

double stranded DNA molecule has one original strand and one new strand

Question 2

DNA in eukaryotic cells?

Answer 2

linear chromosomes containing DNA associated with histones

Question 3

DNA in prokaryotic cells

Answer 3

singular circular chromosome containing naked DNA

Question 4

Two enzymes in DNA replication

Answer 4

helicase and DNA polymerase

Question 5

DNA REPLICATION PROCESS

Answer 5

Helicase unzips DNA strands in a 5’-3’ direction by breaking the hydrogen bonds between base pairs. This requires ATP
DNA polymerase synthesises formation of new bonds between base pairs and floating nucleotides in a 5’-3’ direction

Question 6

What is PCR used for

Answer 6

Amplify the amount of DNA in a sample

Question 7

PCR PROCESS

Answer 7

Denaturation
- DNA sample is heated to ~90 degrees to break the hydrogen bonds between base pairs without helicase

Annealing
- DNA cooled to ~55 degrees to allow primers to attach to exposed strands

Elongation
- DNA heated again to ~75 degrees to allow Taq DNA polymerase to synthesise new covalent bonds between nucleotides.

Question 8

GEL ELECTROPHORESIS purpose?

Answer 8

seperate and isolate fragments of DNA in a sample

Question 9

Gel Electrophoresis PROCESS

Answer 9

1. agarose gel placed in wells at the top. Buffer solution added to allow electricity to be conducted
2. DNA samples loaded into each well. Known fragment is run in Lane 1 to act as a standard
3. Electricity is run in the gel, fragments seperate based on size and charge.
4. Electricity is turned off and UV light is turned on to visualise DNA fragments

Question 10

What is DNA profiling

Answer 10

used to analyse a sample of DNA for crime scene analysis, paternity testing

Question 11

What is a STR

Answer 11

long stretches of repeating elements in non-coding regions of a person’s genome